INFLUENCE OF PARITY-FORBIDDENNESS IN THE ONSET OF MIXED-VALENCE STATEIN SM1-XGDXS

The electronic structure of Sm and Gd in Sm1-xGdxS has been experiment ally studied by the x-ray shift method. Besides the well known strong increase of Sm valence at x approximate to 0.15 (associated with the e lectronic transition to the mixed valence state), a decrease of Sm val ence for x greater than or equal to 0.9 has been observed for the firs t time. This phenomenon is explained as due to the 4f - 5d hybridizati on on neighboring Sm atoms involved in the onset of the mixed valence state, and is interpreted as a manifestation of parity violation forbi ddenness. (C) 1997 American Institute of Physics.